Modified scheelite material for co-firing

ABSTRACT

Disclosed herein are embodiments of low temperature co-fireable scheelite materials which can be used in combination with high dielectric materials, such as nickel zinc ferrite, to form composite structures, in particular for isolators and circulators for radiofrequency components. In some embodiments, the scheelite material can include aluminum oxide for temperature expansion regulation.

INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS

This application is a continuation of U.S. application Ser. No.16/440,221, which, filed Jun. 13, 2019, which claims priority to U.S.App. No. 62/686,191, filed Jun. 18, 2018, the entireties of each ofwhich are incorporated by reference herein.

BACKGROUND Field

Embodiments of the disclosure relate to co-fireable dielectric materialsthat can be formed without the use of adhesives.

Description of the Related Art

Circulators and isolators are passive electronic devices that are usedin high-frequency (e.g., microwave) radio frequency systems to permit asignal to pass in one direction while providing high isolation toreflected energy in the reverse direction. Circulators and isolatorscommonly include a disc-shaped assembly comprising a disc-shaped ferriteor other ferromagnetic ceramic element, disposed concentrically withinan annular dielectric element.

A conventional process for making the above-referenced composite discassemblies is illustrated by the flow diagram of FIG. 1 . At step 12, acylinder is formed from a dielectric ceramic material. At step 14, the(unfired or “green”) cylinder is then fired in a kiln (commonly referredto simply as “firing”). Thus, the ceramic material is “fireable”. Atstep 16, the outside surface of the cylinder is then machined to ensureits outside diameter (OD) is of a selected dimension. Achieving precisedimensions in the assembly elements is important because the dimensionsaffect microwave waveguide characteristics. At step 18, the insidesurface of the cylinder is similarly machined to ensure its insidediameter (ID) is of a selected dimension. In addition, at step 20, a rodis formed from a magnetic ceramic material. At step 22, the rod is thenfired, and at step 24 its surface is machined to a selected OD. The rodOD is slightly less than the cylinder OD so that the rod can be fittedsecurely within the cylinder, as described below. Achieving a close fitthat promotes good adhesion between the rod and cylinder is a reasonthat both the outside surface of the rod and the inside surface of thecylinder are machined to precise tolerances.

At step 26, epoxy adhesive is applied to the one or both of the rod andcylinder. At step 28, the rod is inserted inside the cylinder to form arod-and-cylinder assembly, and the epoxy is allowed to cure (harden), asindicated by step 30. At step 32, the outside surface of therod-and-cylinder assembly is again machined to a precise OD. Lastly, atstep 34, the rod-and-cylinder assembly is sliced into a number of discassemblies. Each disc assembly thus comprises a magnetic ceramic discdisposed concentrically within a dielectric ceramic ring. Each discassembly is typically several millimeters in thickness.

The time involved in machining the inside surface of the cylinder topromote adhesion, applying epoxy to the parts, carefully handling andassembling the epoxy-laden parts, and curing the epoxy, contributes toinefficiency in the process. It would be desirable to provide a moreefficient method for making composite magnetic-dielectric discassemblies.

SUMMARY

Disclosed herein are embodiments of a composite material for use as aradiofrequency component comprising a magnetic garnet material rod, anda ring surrounding the magnetic garnet material rod, the ring beingformed from a scheelite material having a firing temperature of 950° C.or below.

In some embodiments, the scheelite material can have the chemicalformula Li_(0.05)Bi_(0.95)Mo_(0.1)V_(0.9)O₄. In some embodiments, thescheelite material can have the chemical formulaBi_(1-2x-z)R_(z)M′_(x)V_(1-x)M″_(x)O₄, R being a rare earth element La,Ce, Pr, Sm, Nd, Gd, Dy, Tb, Ho, Er, Tm, Yb, Lu, Y or Sc, M′ being Li,Na, or K, and M″ being Mo or W. In some embodiments, the scheelitematerial can have the chemical formula(Na,Li)_(0.5x)Bi_(1-0.5x)(Mo,W)_(x)V_(1-x)O₄, x being between 0 and 0.5.In some embodiments, the scheelite material can include between 1 and 10wt. % aluminum oxide. In some embodiments, the scheelite material caninclude between 2 and 6 wt. % aluminum oxide. In some embodiments, themagnetic garnet material rod can include Bi, Ca, Zr, Y, Fe, and O. Insome embodiments, the scheelite material can include BiVO₄. In someembodiments, the ring can reduce in diameter around the magnetic garnetmaterial rod during firing so that no adhesive is used to connect thering with the magnetic garnet material rod. In some embodiments, thescheelite material can include (Na_(0.35)Bi_(0.65))(Mo_(0.7)V_(0.3))O₄.In some embodiments, the scheelite material can include(Na_(0.2)Bi_(0.8))(Mo_(0.4)V_(0.6))O₄.

Also disclosed herein are embodiments of a method of forming a compositematerial for use as an isolator or circulator in a radiofrequencydevice, the method comprising providing a magnetic garnet material rod,providing an outer ring having a scheelite crystalline structure, theouter ring having a firing temperature of 950° C. or below, entering themagnetic garnet material rod within an aperture in the outer ring, andco-firing the outer ring and the magnetic garnet material rod togetherat a temperature of 950° C. or below to shrink the outer ring around anouter surface of the magnetic garnet material rod without the use ofadhesive or glue and form a composite material.

In some embodiments, the outer ring can have the chemical formulaLi_(0.05)Bi_(0.95)Mo_(0.1)V_(0.9)O₄.

In some embodiments, the scheelite material can have the chemicalformula Bi_(1-2x-z)R_(z)M′_(x)V_(1-x)M″_(x)O₄, R being a rare earthelement La, Ce, Pr, Sm, Nd, Gd, Dy, Tb, Ho, Er, Tm, Yb, Lu, Y or Sc, M′being Li, Na, or K, and M″ being Mo or W. In some embodiments, thescheelite material can have the chemical formula(Na,Li)_(0.5x)Bi_(1-0.5x)(Mo,W)_(x)V_(1-x)O₄, x being between 0 and 0.5.In some embodiments, the scheelite material can include between 1 and 10wt. % aluminum oxide. In some embodiments, the scheelite material caninclude between 2 and 6 wt. % aluminum oxide. In some embodiments, themagnetic garnet material rod can include Bi, Ca, Zr, Y, Fe, and O. Insome embodiments, the scheelite material can include BiVO₄. In someembodiments, the method can further include slicing the compositematerial.

Also disclosed herein are embodiments of a radiofrequency isolator orcirculator comprising a magnetic garnet material rod, and a ringsurrounding the magnetic garnet material rod, the ring being formed froma scheelite material having a firing temperature of 950° C. or below. Insome embodiments, the ring can reduce in diameter around the magneticgarnet material rod during firing so that no adhesive is used to connectthe ring with the magnetic garnet material rod.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a flow diagram of a method for fabricating compositemagnetic-dielectric disc assemblies in accordance with the prior art.

FIG. 2 schematically shows how materials having one or more featuresdescribed herein can be designed, fabricated, and used.

FIG. 3 illustrates a magnetic field v. loss chart.

FIGS. 4A-B illustrate an embodiment of a composite structure having aferrite cylinder within a rectangular prism or cylindrical substrate.

FIGS. 5A-B illustrate an embodiment of a composite tile with a square orcircle shape.

FIG. 6 illustrates an integrated microstrip circulator without a magnet.

FIG. 7 illustrates an integrated microstrip circulator with a magnet.

FIG. 8 illustrates example dielectric constant regimes for certainmaterials.

FIG. 9 illustrates intensity graphs for BiVO₄.

FIG. 10 illustrates intensity graphs forNa_(0.35)Bi_(0.65)Mo_(0.7)V_(0.3)O₄ as calcined.

FIG. 11 illustrates dilatometry testing of scheelite materials.

FIG. 12 illustrates dilatometry testing of BiVO₄ with 1.2% Al₂O₃.

FIG. 13 illustrates an example of a co-firing cycle.

FIG. 14 illustrates dilatometry results for Na₂BiMg₂V₃O₁₂.

FIG. 15 is a schematic diagram of one example of a communicationnetwork.

FIG. 16 is a schematic diagram of one example of a communication linkusing carrier aggregation.

FIG. 17A is a schematic diagram of one example of a downlink channelusing multi-input and multi-output (MIMO) communications.

FIG. 17B is schematic diagram of one example of an uplink channel usingMIMO communications.

FIG. 18 illustrates a schematic of an antenna system.

FIG. 19 illustrates a schematic of an antenna system with an embodimentof an integrated microstrip circulator.

FIG. 20 illustrates a MIMO system incorporating embodiments of thedisclosure.

FIG. 21 is a schematic diagram of one example of a mobile device.

FIG. 22 is a schematic diagram of a power amplifier system according toone embodiment.

FIG. 23 illustrates a method of forming a composite integratedmicrostrip circulator.

FIG. 24 illustrates an embodiment of an integrated microstrip circulatorfor testing.

FIG. 25 illustrates a perspective view of a cellular antenna basestation incorporating embodiments of the disclosure.

FIG. 26 illustrates housing components of a base station incorporatingembodiments of the disclosed material.

FIG. 27 illustrates a cavity filter used in a base station incorporatingembodiments of the material disclosed herein.

FIG. 28 illustrates an embodiment of a circuit board includingembodiments of the material disclosed herein.

DETAILED DESCRIPTION

Disclosed herein are embodiments of low firing dielectric materials.These materials can be advantageously co-fired with high dielectricmaterials to form composites for magnetic-dielectric assemblies, such asfor isolator and circulator applications. These assemblies can be thenincorporated into radiofrequency applications. Advantageously,embodiments of the disclosed materials can be co-fired without needingany adhesives, such as glue, epoxy or other chemical adhesives. Thus,composites formed out of embodiments of the disclosure can be glue free,epoxy free, or adhesive free.

Embodiments of the disclosure could advantageously allow for 5G systems,in particular operating at 3 GHz and above, to form integratedarchitectures which can include different components, such as antennas,circulators, amplifiers, and/or semiconductor based amplifiers. Byallowing for the integration of these components onto a singlesubstrate, this can improve the overall miniaturization of the device.In some embodiments, the disclosed devices can be operable atfrequencies between about 1.8 GHz and about 30 GHz. In some embodiments,the disclosed device can be operable at frequencies of greater thanabout 1, 2, 3, 4, 5, 10, 15, 20, or 25 GHz. In some embodiments, thedisclosed device can be operable at frequencies of less than 30, 25, 20,15, 10, 5, 4, 3, or 2 GHz.

In some embodiments, the integrated architecture can include adirectional coupler and/or isolator in a package size which is not muchlarger than a standard isolator. In some embodiments, the integratedarchitecture can include a high power switch. In addition to using thedielectric tile as the substrate for the impedance transformer, it couldalso be used as the substrate for the coupler, switch and termination

FIG. 2 schematically shows how one or more chemical elements (block 1),chemical compounds (block 2), chemical substances (block 3) and/orchemical mixtures (block 4) can be processed to yield one or morematerials (block 5) having one or more features described herein. Insome embodiments, such materials can be formed into ceramic materials(block 6) configured to include a desirable dielectric property (block7), a magnetic property (block 8).

In some embodiments, a material having one or more of the foregoingproperties can be implemented in applications (block 10) such asradio-frequency (RF) application. Such applications can includeimplementations of one or more features as described herein in devices12. In some applications, such devices can further be implemented inproducts 11. Examples of such devices and/or products are describedherein.

Microstrip Circulators/Isolators

Circulators are passive multiport devices which can receive and transmitdifferent signals, such as microwave or radiofrequency (RF). These portscan be an external waveguide or transmission line which connects to andfrom the circulator. Isolators are similar to circulators, but one ormore of the ports can be blocked off. Hence, circulator and isolator canbe used interchangeably herein as they can be similar in generalstructural. Thus, all discussion below can apply both to circulators andisolators.

Microstrip circulators and isolators are devices known in the artconsist of a thin film circuit deposited over a substrate, such as adielectric ferrite substrate. In some embodiments, one or more ferritediscs can be adhered onto the substrate. Magnet(s) can then be furtherattached to circulate a signal through the ferrite disc.

Further, all-ferrite microstrip circulators have been used as well, inparticular for radar T/R modules. Circuitry can be printed onto the allferrite microstrip circulator and a magnet can be added on top to directthe signal. For example, a metallization pattern is formed onto aferrite substrate. Typically, the metallization pattern consists of acentral disc and multiple transmission lines.

Circulators generally can operate in either of the above or belowresonance operating regions. This is shown in FIG. 3 . In someembodiments, above-resonance frequencies can be advantageous for narrowband, sub 4 GHz circulators. For higher frequencies, the below resonanceregion can be more advantageous.

Microstrip circulators in particular typically work in the belowresonance operating region. They use a very small magnet or can beself-biased, such as in the case of hexagonal ferrites. However, squaretiles can be a difficult shape to magnetize uniformly, in particular forthe all-ferrite microstrip circulators known in the art. Thus, they willoperate close to the low field loss region. When transformers aremounted on the lossy unmagnetized ferrite, performance suffers. Further,increased power will make the poor performance even more known. Thus,circulators known in the art suffer from issues due to the ferrite tilebeing poorly magnetized, leading to poor insertion loss andintermodulation distortion (IMD), and power performance.

Co-Fired Microstrip Circulators/Isolators

Embodiments of the disclosure can improve overall magnetization andreduce performance issues that can occur for currently known microstripcirculators. Generally, the microstrip circulators can be formed byembedding a ferrite disc, such as an oxide ferrite disc made of YIG,directly into a dielectric substrate. The combination can then beco-fired together to form a more solid composite structure. Additionallycircuitry, such as formed from silver or other metalized substances, canbe added. Without the co-firing process, circuit metallization would notbe able to be applied. Embodiments of this disclosure can alleviate someof the significant problems of the art.

Any number of different ferrite disc materials that can be used. In someembodiments, the saturation magnetization levels of the ferrite discmaterial can range between 1000-5000 (or about 1000-about 5000) gauss.

Further, any number of different dielectric substrates known in the artcan be used. The dielectric can be formed from dielectric powder or lowtemperature co-fired ceramic (LTCC) tape. In some embodiments, thedielectric constant can be above 6, 10, 15, 20, 25, 30, 40, 50, or 60.In some embodiments, the dielectric constant can range from 6-30 (orabout 6 to about 30). In some embodiments, the dielectric constant canbe below about 60, 50, 40, 30, 25, 20, 15, or 10.

In particular, to form the composite microstrip circulator 100, amagnetic oxide disc 102, or other magnetic disc, can be inserted into anaperture of a dielectric substrate 104 as shown in FIGS. 4A-B. In someembodiments, the disc 102 can be a cylindrical rod, though theparticular shape is not limiting. The disc 102 can be green, previouslyfired, or not-previously fired.

Further, the substrate 104 can generally be a rectangular prism as shownin FIG. 4A, but other shapes can be used as well such as the cylindershown in FIG. 4B. Embodiments of the substrate 104 are disclosed in moredetail below. Once the disc 102 is inside the substrate 104, thecomponents can be co-fired together, using such a method as discussed inU.S. Pat. No. 7,687,014, hereby incorporated by reference in itsentirety and discussed below. This co-firing process, further detailedbelow, can cause the substrate 104 to shrink around the disc 102 andhold it in place in conjunction with adhesives to form the compositestructure 100. This composite structure 100 can then be sliced to formthe chip structure as shown in FIGS. 5A-B (FIG. 5A showing therectangular prism slice and FIG. 5B showing the cylinder slice).However, in some embodiments, slicing is not performed and thecomponents are co-fired together at their final thickness. In someembodiments, a plurality of different discs can be inserted into asingle substrate in a plurality of different apertures.

Thus, in some embodiments a magnetic oxide disk can be co-fired into asquare or rectangular dielectric substrate, or any other shapedsubstrate, which can then serve as a platform for other components, suchas circuitry. This composite structure can then be magnetized to serveas a microstrip circulator and/or isolator package, for example, or theferrite disc could have been magnetized prior to insertion. In someembodiments, the ferrite disc can be magnetized prior to the co-firingstep.

Once the composite structure is formed, other components can be addedonto the substrate, such as additional thin film circuits and the like.Thus, embodiments of the disclosure can form an integrated solutionwhich can include a directional coupler and/or isolator in a packagesize which is not much larger than a standard isolator. Further,advantageously loss may not be affected by the level of magnetic field,or can at least be reduced. In some embodiments, the disclosedcirculator will be no larger (and depending on the ferrite/dielectriccombination chosen could be smaller) than all current ferrite microstripcirculators.

Thus, using a co-firing process, a ferrite disc can be embedded into adielectric tile, as shown in FIGS. 5A-B. The thin ferrite disc shown inthe figure can be significantly easier to magnetize uniformly than asquare, or other oddly shaped piece, known in the art. In someembodiments, the dielectric tile could be about 25 mm square though theparticular dimensions are not limiting. This can be used in the 3-4 (orabout 3-about 4) GHz region.

Using the dielectric tile, a transformer can then be produced as shownin FIG. 6 . As shown, the substrate 104 has space left over for othercomponent attachments. After forming the transformer, only a smallmagnet needs to be placed on the tile, as shown in FIG. 7 . Thus,assembly time can be much shorter than previously done.

In addition to using the dielectric tile as the substrate for theimpedance transformer, it could also be used as the substrate for thecoupler, switch, and termination. Thus, a number of other components canbe added onto the substrate after co-firing, reducing the overallfootprint of the device. Further, circuit metallization could be added,but only after the device has been co-fired.

Low Temperature Firing Dielectric Materials for Rings

Embodiments of the disclosure can be particularly advantageous for aco-firing process with a magnetic material, such as for the formation ofcirculators/isolators. In particular, they can be high dielectricmagnetic materials with low firing temperatures (e.g., they can befireable at a low temperature). Specifically, a rod of magneticmaterial, such as a nickel-zinc-ferrite material, magnesium ferrite, orother high saturation magnetization spinel ferrite and/or low firingmagnetic garnet material with a high dielectric constant, such as abismuth containing yttrium iron garnet derivative, can be inserted intoan unfired ring formed from embodiments of the disclosed low temperaturefiring dielectric materials, such as shown in FIGS. 4A-B above (104being the ring and 102 being the rod). The high dielectric constantmagnetic garnet material can have a dielectric constant of between 24and 35, such as 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, or 35, butthe particular dielectric constant is not limiting. The ring can be anyof the materials discussed below, such as scheelite, garnet, etc.

The combination of the ring and the rod can then be co-fired together sothat the ring shrinks around the rod. Both of these materials can be“fireable”, meaning they have the ability to be fired or sintered in anoven/kiln/other heating device, for example to a high density. In someembodiments, firing can change one or more properties of the material,such as the ceramic materials discussed herein. After firing, thecombination of ring and rod can be sliced/cut into individualcomponents. Embodiments of these assemblies can be used as isolatorsand/or circulators for radiofrequency applications, such as for 5Gapplications.

Advantageously, this co-firing process can be performed without the useof adhesives/epoxies/glues, or other organic (e.g., carbon-based)polymeric materials, and thus can be considered a “glueless assembly”.For example, a “glue” is not needed to connect the rod to the ring.Previous iterations of the assembly fire the fireable ring separate fromthe fireable rod due to the temperature for firing the ring being toohigh, which can lead to melting, or at least considerably damaging theproperties of the internal rod. Either both segments can be firedseparately, or the ring can be fired first and then the ring/rodassembly is fired together. For each of these approaches, the ring willnot sufficiently shrink around the rod and thus an adhesive will beneeded to keep the ring and the rod attached to one another.

However, the use of adhesives has a number of drawbacks, andadvantageously the disclosed material can form a composite structurewithout the need for such adhesive as the rod and ring can be co-firedtogether. For example, it is extremely difficult, if not impossible, tometallize the assembly once there is adhesive. This is because thetemperature required for metallization is much higher than the usetemperature for the adhesive, causing the adhesive to melt and/or loseadhesive.

Further, the glue is lossy, increasing the insertion loss of gluedcomponents. The dielectric loss of the glue at high frequencies isgreater than the magnetic or the dielectric material.

In some embodiments, the material can have c′ of less than 10 (or lessthan about 10). Thus, embodiments of the disclosure can be used for 5Gbelow resonance applications. It can be advantageous to avoid moding andto offset the impedance effect of thinner substrates also used at highfrequencies. Accordingly, values below 10 (or below about 10) are usedfor above 20 GHz frequencies.

As an example, embodiments of the material as a ring can be suitable forco-firing with a rod material of high magnetization spinels (for examplenickel zinc ferrites) such as disclosed in U.S. Pat. Pub. No.2017/0098885, hereby incorporated by reference in its entirety, inparticular for high frequency (5G) applications. Additionally, the ringmaterial can be co-fired with high dielectric constant materials such asdisclosed in U.S. Pat. Pub. No. 2018/0016155, the entirety of which ishereby incorporated by reference in its entirety. The high dielectricconstant magnetic rod can be a bismuth substituted high dielectricconstant magnetic garnet. Standard bismuth doped high dielectricconstant garnet materials such as Bi containing garnet materialsdescribed in numerous previous patent applications. Y—Bi—Ca—Zr—V—Fe—Osinters around 950° C. Thus, disclosed herein are ways to lower thefiring temperature of scheelite material so that it can be co-fired withthe nickel zinc ferrite at an appropriate temperature range.

As mentioned, the co-fireable ring material can be based on a scheelitestructure or scheelite style material (e.g., a crystalline compoundwhich contains a scheelite atomic arrangement). This can includecrystalline compounds which contain a scheelite atomic arrangement, andthe term scheelite structure, scheelite, or scheelite style material canbe used interchangeably. FIG. 8 illustrates dielectric constant regimesby material family for low firing (<800° C.) oxides. In someembodiments, the scheelite material have the chemical formula BiVO₄.

In some embodiments, the material having the scheelite structure can beBi_(1-2x-z)R_(z)M′_(x)V_(1-x)M″_(2x)O₄ where R is a rare earth elementLa, Ce, Pr, Sm, Nd, Gd, Dy, Tb, Ho, Er, Tm, Yb, Lu, Y or Sc, M′ is Li,Na, or K and M″ is Mo or W. In some embodiments, 0<z<0.7 and 0<x<0.5.

In some embodiments, the scheelite material can have the chemicalformula (Na,Li)_(0.5x)Bi_(1-0.5x)(Mo,W)_(x)V_(1-x)O₄. In someembodiments, 0<x<0.5.

In some embodiments, scheelites may have a low firing temperature (<850°C., <900° C.) a low dielectric loss tangent (<0.001 at 3 GHz), and withsuitable substitutions into the structure may exhibit a range ofdielectric constants from 8 to 70 (or about 8 to about 70), between 10and 60 (or about 10 to about 60), between 20 and 50 (or about 20 andabout 50), or between 30 and 40 (or between about 30 and about 40). Insome embodiments, the scheelites may exhibit a dielectric constant of 8,10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, or 70 (or about 8, about10, about 15, about 20, about 25, about 30, about 35, about 40, about45, about 50, about 55, about 60, about 65, or about 70).

The scheelite material in particular can be used as a low dielectricconstant co-fireable material to fire with high dielectric constantmaterials, for example garnet and/or Bi doped materials, or any of thehigh magnetic rod materials discussed herein. It can be advantageous touse this material to avoid moding, and to offset the impedance effect ofthinner substrates also necessary at high frequencies. The scheelitematerial can further be particularly useful for high frequencymicrostrip or surface integrated waveguide designs, for example due tothe lowered temperature which allows for chemical compatibility and awider range of dielectric constants.

In some embodiments, aluminum oxide, such as Al₂O₃, can be added intothe ring materials, such as the scheelite material, garnet material,spinel material, pyrochlore material, etc. discussed herein. Forexample, the aluminum oxide can be blended into the ring material asaluminum oxide, such as by combining different powders. In someembodiments, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 (or about 1, about 2,about 3, about 4, about 5, about 6, about 7, about 8, about 9, or about10) wt. % of aluminum oxide can be incorporated into the scheelitematerial. In some embodiments, 1.2 (or about 1.2) wt. % of aluminumoxide can be incorporated into the scheelite material. In someembodiments, greater than 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10 (or about 1,about 2, about 3, about 4, about 5, about 6, about 7, about 8, about 9,or about 10) wt. % of aluminum oxide can be incorporated into thescheelite material. In some embodiments, less than 1, 2, 3, 4, 5, 6, 7,8, 9, or 10 (or about 1, about 2, about 3, about 4, about 5, about 6,about 7, about 8, about 9, or about 10) wt. % of aluminum oxide can beincorporated into the scheelite material. In some embodiments, between 2and 6 (or between about 2 and about 6) wt. % of aluminum oxide can beincorporated into the scheelite material. In some embodiments, 1-10 wt.% (or about 1 to about 10 wt. %) aluminum oxide can be added into thescheelite material. The incorporation of aluminum oxide can regulatethermal expansion behavior and prevent cracking. For example, it canallow the scheelite material to better match a thermal expansionmaterial of a high dielectric, such as a bismuth rich high dielectricconstant garnet, as compared to undoped scheelite material, therebyallowing for successful co-firing without cracking. Specifically, thecracking can be prevented by regulating thermal expansion.

Table 1 illustrates a number of different scheelite materials and theirproperties. In some embodiments, tungstates can have lower dielectricconstants than corresponding molybdates, both of which can have ascheelite structure.

TABLE 1 Scheelite Materials Firing τ_(F) Temp. Dielectric (ppm/Composition (° C.) Constant Q ° C.) (K_(0.5)La_(0.5))MoO₄ 680 10.3 59000−81 LiKSm₂(MoO₄)₄ 620 11.5 39000 −16 (Li_(0.5)Sm_(0.5))MoO₄ 640 19.94570 +231 (Li_(0.5)Nd_(0.5))MoO₄ 660 20.3 3000 +235(Li_(0.5)Ce_(0.5))MoO₄ 580 20.6 1990 +228(Ag_(0.5)Bi_(0.5))(Mo_(0.5)W_(0.5))O₄ 500 26.3 10000 +20(Li_(0.5)Bi_(0.5))WO₄ 650 26.5 16400 +70 (Ag_(0.5)Bi_(0.5))MoO₄ 690 30.412600 +52 (Li_(0.5)Bi_(0.5))(Mo_(0.4)W_(0.6))O₄ 620 31.5 8500 +20(Na_(0.5)Bi_(0.5))MoO₄ 690 34.4 12300 +43 (K_(0.5)Bi_(0.5))MoO₄ 630 37.04000 +117 (Na_(0.35)Bi_(0.65))(MO_(0.7)V_(0.3))O₄ 680 44.0 6100 N/A(Li_(0.5)Bi_(0.5))MoO₄ 560 44.4 3200 N/A(Na_(0.275)Bi_(0.725))(Mo_(0.55)V_(0.45))O₄ 700 51 5500 N/A(Na_(0.2)Bi_(0.8))(Mo_(0.4)V_(0.6))O₄ 700 58 5000 N/A(Li_(0.05)Bi_(0.95))(Mo_(0.1)V_(0.9))O₄ 650 81 1000 N/A

In some embodiments, the disclosed scheelite material can have a Q rangeof greater than 900, 1000, 1100, 1200, or 1300 (or greater than about900, about 1000, about 1100, about 1200, or about 1300. In someembodiments, the disclosed scheelite material can have a Q range of lessthan 900, 1000, 1100, 1200, or 1300 (or less than about 900, 1000, 1100,1200, or 1300.

In some embodiments, the disclosed scheelite material can have adielectric constant of between 10 and 100 (or between about 10 and about100). In some embodiments, the disclosed scheelite material can have adielectric constant of greater than 10, 20, 30, 40, 50, 60, 70, 80, 90,or 100 (or greater than about 10, about 20, about 30, about 40, about50, about 60, about 70, about 80, about 90, or about 100). In someembodiments, the disclosed scheelite material can have a dielectricconstant of less than 20, 30, 40, 50, 60, 70, 80, 90, or 100 (or lessthan about 20, about 30, about 40, about 50, about 60, about 70, about80, about 90, or about 100).

In some embodiments, the disclosed scheelite material can have a firingtemperature of below 900, 850, 800, or 750° C. (or below about 900,about 850, about 800, or about 750° C.). In some embodiments, thedisclosed scheelite material can have a firing temperature of greaterthan 900, 850, 800, or 750° C. (or greater than about 850, about 800, orabout 750° C.). In some embodiments, the disclosed scheelite materialcan have a firing temperature of 775° C. (or about 775° C.).

Table 2 illustrates experimental results of using a scheelite material.Further, Table 2 discloses potential device application for thescheelite materials.

TABLE 2 Scheelite Experimental Results Firing Dielectric Temperature, QFProduct, Material Constant ° C. THz Device ApplicationNa_(0.2)Bi_(0.8)Mo_(0.4)V_(0.6)O₄ 56.33 725 4.157 Triplate aboveresonance or below resonance; Microstrip below resonanceLi_(0.05)Bi_(0.95)Mo_(0.1)V_(0.9)O₄ 73.23 750 4.921 Triplate aboveresonance or below resonance; Microstrip below resonance(Li_(0.5)Bi_(0.5))(Mo_(0.4)W_(0.6))O₄ 30 ? ? Triplate below resonance;Microstrip below resonance (Na_(0.5)Bi_(0.5))MoO₄ 16.19 700 3.288Substrate Integrated Waveguides (SIW) below resonanceNa_(0.35)Bi_(0.65)Mo_(0.7)V_(0.3)O₄ 43 750 Triplate above resonance orbelow resonance; Microstrip below resonance

Table 3 illustrates particular scheelite based compositions which can beadvantageously co-fired with TTHiE high dielectric materials.

TABLE 3 Scheelite based TTHiE Co-Fired Compositions Expected FiringDielectric Temp. Soak Fired OD Length Material Constant MS ° C. (hr)Density ε′ Q fo Shrinkage Shrinkage Na_(0.2)Bi_(0.8)Mo_(0.4)V_(0.6)O₄Li_(0.05)Bi_(0.95)Mo_(0.1)V_(0.9)O₄ 70 1429561 750 4 6.454 73.23 15843107.7 8.10% 7.23% Li_(0.5)Bi_(0.5)Mo_(0.4)W_(0.6)O₄ 30Na_(0.5)Bi_(0.5)MoO₄ 20 1429563 700 4 4.431 16.19 508 6473.3 4.52% 3.38%Na₂BiMg₂V₃O₁₂ 25 1429562 750 4 4.178 24.04 807 5359.1 8.10% 7.76%Na_(0.35)Bi_(0.65)Mo_(0.7)V_(0.3)O₄ 43 725 4 12.28% 11.29%Na_(0.35)Bi_(0.65)Mo_(0.7)V_(0.3)O₄ 43 725 4 10.93% 12.50% BiVO₄ 80 7004 5.074 11.95% 11.17% BiVO₄ 80 700 4 4.926 10.82% 11.43% BiVO₄ 80 800 46.605 19.26% 18.39% BiVO₄ 80 800 4 6.554 18.94% 18.39% BiVO₄ 80 850 46.605 40 19.09% 17.39% BiVO₄ 80 850 4 6.610 19.09% 17.97%Na_(0.35)Bi_(0.65)Mo_(0.7)V_(0.3)O₄ 43 725 4 12.28% 11.29%Na_(0.35)Bi_(0.65)Mo_(0.7)V_(0.3)O₄ 43 725 4 10.93% 12.50%Na_(0.35)Bi_(0.65)Mo_(0.7)V_(0.3)O₄ 43 750 4 14.92% 15.09%Na_(0.35)Bi_(0.65)Mo_(0.7)V_(0.3)O₄ 43 750 4 13.73% 13.29%Na_(0.35)Bi_(0.65)Mo_(0.7)V_(0.3)O₄ 43 750 4 4.77 13.81% 13.29%Na_(0.35)Bi_(0.65)Mo_(0.7)V_(0.3)O₄ 43 750 4 4.80 13.73% 13.74%

As shown above, bismuth vanadate (BiVO₄) can be a particularly usefulscheelite material. In some embodiments, sodium or molybdenum can beadded into the material.

Table 4 illustrates other examples of materials having a scheelitestructure which may be useful for co-firing.

TABLE 4 Materials Having Scheelite Structure Dielectric Firing ScheeliteConstant Temperature (° C.) Na_(0.2)Bi_(0.8)Mo_(0.4)V_(0.6)O₄ 57 675Li_(0.05)Bi_(0.95)Mo_(0.1)V_(0.9)O₄ 70 675Li_(0.5)Bi_(0.5)Mo_(0.4)W_(0.6)O₄ 30 600 Li_(0.5)Sm_(0.5)MoO₄ 25 640

FIG. 9 illustrates an x-ray diffraction trace for BiVO₄. FIG. 10illustrates intensity graphs for Na_(0.35)Bi_(0.65)Mo_(0.7)V_(0.3)O₄ ascalcined. Both figures indicate that the material has a scheelitestructure and only a scheelite structure is present.

FIG. 11 illustrates a dilatometry testing of scheelite materials. TheTTHIE-1950 is a Bi—Ca—Zr—Y—Fe—O material. It can be advantageous for themean alpha of the non-TTHIE materials to match as closely as possible tothe mean alpha of the TTHiE material, such as U.S. Pat. Nos. 9,263,175and 9,527,776, the entirety of each of which is hereby incorporated byreference in its entirety.

FIG. 12 illustrates dilatometry testing of BiVO₄ with 1.2% Al₂O₃. Asshown, the thermal expansion coefficient is a reasonable value to beco-fired with magnetic materials.

In some embodiments, the disclosed scheelite material can have a meanalpha within 1%, 5%, or 10% (or within about 1%, about 5%, or about 10%)of the TTHI material. In some embodiments, the mean alpha can be in therange of 6-13 (or about 6-about 13) ppm/degree C., such as 6, 7, 8, 9,10, 11, 12, or 13 (or about 6, about 7, about 8, about 9, about 10,about 11, about 12, or about 13) ppm/degree C.

FIG. 13 illustrates the co-fire ideal cycle with garnet and dielectricfactors. The ideal is that the OD of the pre-fired garnet rod is exactly(or about exactly) the same as the ID of the pressed dielectric tube atthe end of the co-firing phase, but before cooling. Since the garnet hasa fixed expansion, this is done by adjusting the shrinkage and initialsize of the dielectric, thru control of green density. Diffusion occursat the co-fire temperature after the garnet and dielectric are incontact, forming a bond; too much diffusion may cause dielectric loss.The garnet and dielectric remain in contact thru cooling, because theirexpansion (contraction) coefficients are the same, retaining the bond.

In some embodiments, other ring materials can be used for co-firinginstead of scheelites, with or without the aluminum oxide discussedabove. For example, spinels structures can be used as well. Table 5illustrates potential spinel materials that can be used.

TABLE 5 Garnet Materials for Co-firing Firing Temperature Dielectric Qfproduct Composition (° C.) Constant (THz) t_(F) (ppm/° C.) Na₂MoO₄ 6004.1 46.9 −76 Li₂MoO₄ 540 5.5 59.8 −160 Li₂WO₄ 640 5.5 97.3 −146 LiMgVO₄700 8.9 23.8 −140

Other useful ring materials can be garnets, with or without the aluminumoxide discussed above, which are isostructural with the high dielectricnickel materials discussed above. Table 6 illustrates potential garnetmaterials.

TABLE 6 Spinel Materials for Co-firing Firing Qf Temp. Dielectricproduct t_(F) (ppm/ Composition (° C.) Constant (THz) ° C.)Li_(0.16)Na_(0.84)Ca₂Mg₂V₃O₁₂ 920 9.9 45.5 +2 LiCa₃MgV₃O₁₂ 900 10.5 74.7−61 LiMg₄V₃O₁₂ 740 10.7 24.0 −11.7 LiCa₃ZnV₃O₁₂ 900 11.5 81.1 −72Na₂YMg₂V₃O₁₂ 850 12.3 23.2 −4.1 NaMg₄V₃O₁₂ 690 12.5 35.9 −58.1Na₂BiMg₂V₃O₁₂ 750 24? 4.4

FIG. 14 illustrates dilatometry results for Na₂BiMg₂V₃O₁₂.

Another useful ring material can include pyrochlore materials, with orwithout the aluminum oxide discussed above. Table 7 illustratespotential pyrochlore materials which can be used.

TABLE 7 Pyrochlore Materials for Co-firing Firing Qf tF Temp. Dielectricproduct (ppm/ Composition (° C.) Constant (THz) ° C.)(Bi_(1.92)Zn_(0.08))(Zn_(0.64)Nb_(1.36))O₇ 1000 75.0 1800(Bi_(1.92)Ca_(0.08))(Zn_(0.64)Nb_(1.36))O₇ 960 76.0 3900Bi₂(Zn_(1/3)Nb_(2/3−x)V_(x))O7 (x = 850 78.5 3780 .001-.003)Bi₁₈(Zn_(0.725)Ca_(0.275))₈Nb₁₂O₆₅ 925 79 1000 +3.2Bi₃(Nb_(0.9)V_(0.1))O₇ 870 80 600 −22Bi₂(Zn_(0.5)Mg_(0.5))_(2/3)Nb_(4/3)O₇ 900 98.0 3000Bi_(1.5)Zn_(0.92)Nb_(1.5)O_(6.92) + 850 148.0 120 0.6% V₂O₅

In some embodiments, higher energy comminution can reduce the firingtemperatures to around 850° C., or 850° C. or below by increasing thesurface area of the powder making it more reactive. In some embodiments,the pyrochlore materials can have a dielectric constant range of 60-100.

Table 8 illustrates device applications for co-fire ferrite/dielectriccombinations. It will be understood that the below table shows examplesonly, and the disclosure is not limited to the particular devices shownbelow.

TABLE 8 Example Uses of Co-Fired Materials Operating Dielectric's RFDevice mode, above Co-fire dielectric Transmission or below FrequencyFunctional Ferrite constant line FMR Range Requirement Conventional20-30 Stripline Above 600 MHz to Replace Garnet, 1200 ~3.5 GHzProduction to 1950 ID Gauss grind/glue; allow metallization Spinel, upto  8-20 SIW, Below 10-60+ GHz 5G 5000 Gauss Microstrip componentcompatibility, subsystem integration TTHiE,    45-120+ Stripline Above600 MHz to Replace 1150-1950 ~3.5 GHz Production Gauss ID grind/glue;allow metallization TTHiE 400- 20-30; Stripline, Below 1.8-6 GHz    5G1950 Gauss    45-120+ Microstrip components/ subsystem integration

5G Applications

Embodiments of the disclosed composite microstrip circulators can beparticularly advantageous for 5′ generation wireless system (5G)applications, though could also be used for early 4G and 3G applicationsas well. 5G technology is also referred to herein as 5G New Radio (NR).5G networks can provide for significantly higher capacities than current4G system, which allows for a larger number of consumers in an area.This can further improve uploading/downloading limits and requirements.In particular, the large number of circulators, such as those describedherein, needed for 5G (typically 1 per front end module or FEM) requiresfurther integration of components. The disclosed embodiments ofcirculators can allow for this integration and thus can be particularlyadvantageous. Other components in the front end module will bemicrostrip or SMT based.

Preliminary specifications for 5G NR support a variety of features, suchas communications over millimeter wave spectrum, beam formingcapability, high spectral efficiency waveforms, low latencycommunications, multiple radio numerology, and/or non-orthogonalmultiple access (NOMA). Although such RF functionalities offerflexibility to networks and enhance user data rates, supporting suchfeatures can pose a number of technical challenges.

The teachings herein are applicable to a wide variety of communicationsystems, including, but not limited to, communication systems usingadvanced cellular technologies, such as LTE-Advanced, LTE-Advanced Pro,and/or 5G NR.

FIG. 15 is a schematic diagram of one example of a communication network10. The communication network 10 includes a macro cell base station 1, amobile device 2, a small cell base station 3, and a stationary wirelessdevice 4.

The illustrated communication network 10 of FIG. 15 supportscommunications using a variety of technologies, including, for example,4G LTE, 5G NR, and wireless local area network (WLAN), such as Wi-Fi.Although various examples of supported communication technologies areshown, the communication network 10 can be adapted to support a widevariety of communication technologies.

Various communication links of the communication network 10 have beendepicted in FIG. 15 . The communication links can be duplexed in a widevariety of ways, including, for example, using frequency-divisionduplexing (FDD) and/or time-division duplexing (TDD). FDD is a type ofradio frequency communications that uses different frequencies fortransmitting and receiving signals. FDD can provide a number ofadvantages, such as high data rates and low latency. In contrast, TDD isa type of radio frequency communications that uses about the samefrequency for transmitting and receiving signals, and in which transmitand receive communications are switched in time. TDD can provide anumber of advantages, such as efficient use of spectrum and variableallocation of throughput between transmit and receive directions.

As shown in FIG. 15 , the mobile device 2 communicates with the macrocell base station 1 over a communication link that uses a combination of4G LTE and 5G NR technologies. The mobile device 2 also communicateswith the small cell base station 3 which can include embodiments of thedisclosure. In the illustrated example, the mobile device 2 and smallcell base station 3 communicate over a communication link that uses 5GNR, 4G LTE, and Wi-Fi technologies.

In certain implementations, the mobile device 2 communicates with themacro cell base station 2 and the small cell base station 3 using 5G NRtechnology over one or more frequency bands that are less than 6Gigahertz (GHz). In one embodiment, the mobile device 2 supports a HPUEpower class specification.

The illustrated small cell base station 3, incorporating embodiments ofthe disclosure, also communicates with a stationary wireless device 4.The small cell base station 3 can be used, for example, to providebroadband service using 5G NR technology over one or more frequencybands above 6 GHz, including, for example, millimeter wave bands in thefrequency range of 30 GHz to 300 GHz.

In certain implementations, the small cell base station 3 communicateswith the stationary wireless device 4 using beamforming. For example,beamforming can be used to focus signal strength to overcome pathlosses, such as high loss associated with communicating over millimeterwave frequencies.

The communication network 10 of FIG. 15 includes the macro cell basestation 1, which can include embodiments of the disclosure, and thesmall cell base station 3. In certain implementations, the small cellbase station 3 can operate with relatively lower power, shorter range,and/or with fewer concurrent users relative to the macro cell basestation 1. The small cell base station 3 can also be referred to as afemtocell, a picocell, or a microcell.

Although the communication network 10 is illustrated as including twobase stations, the communication network 10 can be implemented toinclude more or fewer base stations and/or base stations of other types.

The communication network 10 of FIG. 15 is illustrated as including onemobile device and one stationary wireless device. The mobile device 2and the stationary wireless device 4 illustrate two examples of userdevices or user equipment (UE). Although the communication network 10 isillustrated as including two user devices, the communication network 10can be used to communicate with more or fewer user devices and/or userdevices of other types. For example, user devices can include mobilephones, tablets, laptops, IoT devices, wearable electronics, and/or awide variety of other communications devices.

User devices of the communication network 10 can share available networkresources (for instance, available frequency spectrum) in a wide varietyof ways.

Enhanced mobile broadband (eMBB) refers to technology for growing systemcapacity of LTE networks. For example, eMBB can refer to communicationswith a peak data rate of at least 10 Gbps and a minimum of 100 Mbps foreach user device. Ultra-reliable low latency communications (uRLLC)refers to technology for communication with very low latency, forinstance, less than 2 ms. uRLLC can be used for mission-criticalcommunications such as for autonomous driving and/or remote surgeryapplications. Massive machine-type communications (mMTC) refers to lowcost and low data rate communications associated with wirelessconnections to everyday objects, such as those associated with Internetof Things (IoT) applications.

The communication network 10 of FIG. 15 can be used to support a widevariety of advanced communication features, including, but not limitedto eMBB, uRLLC, and/or mMTC.

A peak data rate of a communication link (for instance, between a basestation and a user device) depends on a variety of factors. For example,peak data rate can be affected by channel bandwidth, modulation order, anumber of component carriers, and/or a number of antennas used forcommunications.

For instance, in certain implementations, a data rate of a communicationlink can be about equal to M*Blog₂(1+S/N), where M is the number ofcommunication channels, B is the channel bandwidth, and S/N is thesignal-to-noise ratio (SNR).

Accordingly, data rate of a communication link can be increased byincreasing the number of communication channels (for instance,transmitting and receiving using multiple antennas), using widerbandwidth (for instance, by aggregating carriers), and/or improving SNR(for instance, by increasing transmit power and/or improving receiversensitivity).

5G NR communication systems can employ a wide variety of techniques forenhancing data rate and/or communication performance.

FIG. 16 is a schematic diagram of one example of a communication linkusing carrier aggregation. Carrier aggregation can be used to widenbandwidth of the communication link by supporting communications overmultiple frequency carriers, thereby increasing user data rates andenhancing network capacity by utilizing fragmented spectrum allocations.

In the illustrated example, the communication link is provided between abase station 21 and a mobile device 22. As shown in FIG. 16 thecommunications link includes a downlink channel used for RFcommunications from the base station 21 to the mobile device 22, and anuplink channel used for RF communications from the mobile device 22 tothe base station 21.

Although FIG. 16 illustrates carrier aggregation in the context of FDDcommunications, carrier aggregation can also be used for TDDcommunications.

In certain implementations, a communication link can provideasymmetrical data rates for a downlink channel and an uplink channel.For example, a communication link can be used to support a relativelyhigh downlink data rate to enable high speed streaming of multimediacontent to a mobile device, while providing a relatively slower datarate for uploading data from the mobile device to the cloud.

In the illustrated example, the base station 21 and the mobile device 22communicate via carrier aggregation, which can be used to selectivelyincrease bandwidth of the communication link. Carrier aggregationincludes contiguous aggregation, in which contiguous carriers within thesame operating frequency band are aggregated. Carrier aggregation canalso be non-contiguous, and can include carriers separated in frequencywithin a common band or in different bands.

In the example shown in FIG. 16 , the uplink channel includes threeaggregated component carriers f_(uL1), f_(uL2), and f_(uL3).Additionally, the downlink channel includes five aggregated componentcarriers f_(DL1), f_(DL2), f_(DL3), f_(DL4), and f_(DL5). Although oneexample of component carrier aggregation is shown, more or fewercarriers can be aggregated for uplink and/or downlink. Moreover, anumber of aggregated carriers can be varied over time to achieve desireduplink and downlink data rates.

For example, a number of aggregated carriers for uplink and/or downlinkcommunications with respect to a particular mobile device can changeover time. For example, the number of aggregated carriers can change asthe device moves through the communication network and/or as networkusage changes over time.

With reference to FIG. 16 , the individual component carriers used incarrier aggregation can be of a variety of frequencies, including, forexample, frequency carriers in the same band or in multiple bands.Additionally, carrier aggregation is applicable to implementations inwhich the individual component carriers are of about the same bandwidthas well as to implementations in which the individual component carriershave different bandwidths.

FIG. 17A is a schematic diagram of one example of a downlink channelusing multi-input and multi-output (MIMO) communications. FIG. 17B isschematic diagram of one example of an uplink channel using MIMOcommunications.

MIMO communications use multiple antennas for simultaneouslycommunicating multiple data streams over common frequency spectrum. Incertain implementations, the data streams operate with differentreference signals to enhance data reception at the receiver. MIMOcommunications benefit from higher SNR, improved coding, and/or reducedsignal interference due to spatial multiplexing differences of the radioenvironment.

MIMO order refers to a number of separate data streams sent or received.For instance, MIMO order for downlink communications can be described bya number of transmit antennas of a base station and a number of receiveantennas for UE, such as a mobile device. For example, two-by-two (2×2)DL MIMO refers to MIMO downlink communications using two base stationantennas and two UE antennas. Additionally, four-by-four (4×4) DL MIMOrefers to MIMO downlink communications using four base station antennasand four UE antennas.

In the example shown in FIG. 17A, downlink MIMO communications areprovided by transmitting using M antennas 43 a, 43 b, 43 c, . . . 43 mof the base station 41 and receiving using N antennas 44 a, 44 b, 44 c,. . . 44 n of the mobile device 42. Accordingly, FIG. 17A illustrates anexample of M×N DL MIMO.

Likewise, MIMO order for uplink communications can be described by anumber of transmit antennas of UE, such as a mobile device, and a numberof receive antennas of a base station. For example, 2×2 UL MIMO refersto MIMO uplink communications using two UE antennas and two base stationantennas. Additionally, 4×4 UL MIMO refers to MIMO uplink communicationsusing four UE antennas and four base station antennas.

In the example shown in FIG. 17B, uplink MIMO communications areprovided by transmitting using N antennas 44 a, 44 b, 44 c, . . . 44 nof the mobile device 42 and receiving using M antennas 43 a, 43 b, 43 c,. . . 43 m of the base station 41. Accordingly, FIG. 17B illustrates anexample of N×M UL MIMO.

By increasing the level or order of MIMO, bandwidth of an uplink channeland/or a downlink channel can be increased.

Although illustrated in the context of FDD, MIMO communications are alsoapplicable communication links using TDD.

For these 5G networks, one form of base station will be massive multipleinput, multiple output (MIMO) based, with an array of perhaps 64-128antennas capable of multi-beam forming to interact with handheldterminals at very high data rates. Thus, embodiments of the disclosurecan be incorporated into the base stations to provide for high capacityapplications.

This approach is similar to radar phased array T/R modules, withindividual transceivers for each antenna element, although massive MIMOis not a phased array in the radar sense. The objective is optimumcoherent signal strength at the terminal(s) rather than directionfinding. Further, signal separation will be time division (TD) based,requiring a means of duplexing/switching to separate Tx and Rx signals

For discussion, it is assumed that there is one Tx, one Rx module, oneduplexing circulator and one antenna filter per antenna. However, otherconfigurations can be used as well.

FIG. 18 shows a simplified version of an RF transmission system,omitting drivers and switching logic. As shown, the system can include anumber of different components, including a circulator. Thus,embodiments of the disclosure can be used as the circulator in the RFsystem, either for newly created systems or as improved replacements forthe previous systems. Specifically, embodiments of the disclosure relateto hybrid solutions using a stripline circulator, and microstrip orstripline topology for the remaining components.

FIG. 19 illustrates the integrated component of FIGS. 5A-B discussedabove onto the simplified RF antenna structure. As shown, the substratecan include the co-fired ferrite/dielectric tile for the circulator. Inaddition, a coupler, switch, and load can also be applied to thedielectric tile outside of the ferrite. The conductors and the groundplane could be in a thick film silver. In some embodiments, thecirculator subassembly can also be integrated with the power amplifier(PA) and loud noise amplifier (LNA) modules.

Embodiments of the disclosure can have advantages over circulators knownin the art. For example,

-   -   Couplers and other transmission lines have much lower insertion        loss compared with other couplers, such as semiconductor        couplers    -   Coupling is more consistent    -   Loads can dissipate heat more easily compared with soft        substrate    -   Circulators have lower loss than all-ferrite substrate based        devices    -   The dielectric is temperature stable, assisting the coupler and        circulator's performance    -   The size of the devices can be reduced by using higher        dielectric constant ceramic dielectric if required

Further, embodiments of the ceramic circulator can have the followingadvantages:

-   -   Heat/power dissipation/thermal conductivity for PA and load    -   Isotropic dielectric (except TTB) for coupler/filter design    -   Range of dielectric constant (4-100+) for size reduction    -   Low dielectric loss (coupler/filter)    -   Tight dielectric constant tolerance (coupler/filter/antenna)    -   Stable dielectric constant over temperature        (coupler/filter/circulator)    -   Modest Cost

On the other hand, soft substrate (e.g., softboards) can have thefollowing disadvantages:

-   -   Poor conductivity due to plastic conductivity    -   Anisotropic (xy versus z direction)    -   Only 3-10 with some, fixed with others    -   Higher losses    -   Looser tolerances    -   Unstable over temperature

Accordingly, embodiments of the disclosure can have significantadvantages over circulators previously known in the art.

FIG. 20 illustrates another embodiment of a MIMO system that thedisclosed microstrip circulators can be incorporated into. With theadvent of massive MIMO for 5G system the current antennas will bereplaced with antenna arrays with, for example, 64 array elements. Eachelement can be fed by a separate front end module (FEM).

FIG. 21 is a schematic diagram of one example of a mobile device 800.The mobile device 800 includes a baseband system 801, a transceiver 802,a front end system 803, antennas 804, a power management system 805, amemory 806, a user interface 807, and a battery 808 and can interactwith the base stations including embodiments of the microstripcirculators disclosed herein.

The mobile device 800 can be used communicate using a wide variety ofcommunications technologies, including, but not limited to, 2G, 3G, 4G(including LTE, LTE-Advanced, and LTE-Advanced Pro), 5G NR, WLAN (forinstance, Wi-Fi), WPAN (for instance, Bluetooth and ZigBee), and/or GPStechnologies.

The transceiver 802 generates RF signals for transmission and processesincoming RF signals received from the antennas 804. It will beunderstood that various functionalities associated with the transmissionand receiving of RF signals can be achieved by one or more componentsthat are collectively represented in FIG. 21 as the transceiver 802. Inone example, separate components (for instance, separate circuits ordies) can be provided for handling certain types of RF signals.

In certain implementations, the mobile device 800 supports carrieraggregation, thereby providing flexibility to increase peak data rates.Carrier aggregation can be used for both Frequency Division Duplexing(FDD) and Time Division Duplexing (TDD), and may be used to aggregate aplurality of carriers or channels. Carrier aggregation includescontiguous aggregation, in which contiguous carriers within the sameoperating frequency band are aggregated. Carrier aggregation can also benon-contiguous, and can include carriers separated in frequency within acommon band or in different bands.

The antennas 804 can include antennas used for a wide variety of typesof communications. For example, the antennas 804 can include antennasassociated transmitting and/or receiving signals associated with a widevariety of frequencies and communications standards.

In certain implementations, the antennas 804 support MIMO communicationsand/or switched diversity communications. For example, MIMOcommunications use multiple antennas for communicating multiple datastreams over a single radio frequency channel. MIMO communicationsbenefit from higher signal to noise ratio, improved coding, and/orreduced signal interference due to spatial multiplexing differences ofthe radio environment. Switched diversity refers to communications inwhich a particular antenna is selected for operation at a particulartime. For example, a switch can be used to select a particular antennafrom a group of antennas based on a variety of factors, such as anobserved bit error rate and/or a signal strength indicator.

FIG. 22 is a schematic diagram of a power amplifier system 840 accordingto one embodiment. The illustrated power amplifier system 840 includes abaseband processor 821, a transmitter 822, a power amplifier (PA) 823, adirectional coupler 824, a bandpass filter 825, an antenna 826, a PAbias control circuit 827, and a PA supply control circuit 828. Theillustrated transmitter 822 includes an I/Q modulator 837, a mixer 838,and an analog-to-digital converter (ADC) 839. In certainimplementations, the transmitter 822 is included in a transceiver suchthat both transmit and receive functionality is provided. Embodiments ofthe disclosed microstrip circulators can be incorporated into the poweramplifier system.

Methodology

Disclosed herein are embodiments of a process for making an integratedmicrostrip component. FIG. 23 discloses an embodiment of a process 300that can be used.

Returning to FIG. 23 , at step 302, a ferrite disc or cylinder can beformed from a magnetic ceramic material by any suitable conventionalprocess known in the art for making such elements, i.e., magnetic oxidesof the types used in high frequency electronic components. Similarly, atstep 304, a substrate can be formed from a dielectric material by anysuitable conventional process. In some embodiments, the ferrite disc canbe sintered by firing it in a kiln. Some examples of materials andfiring temperatures are set forth below, following this process flowdescription. However, persons skilled in the art to which the inventionrelates understand that the materials and processes by which magneticceramic and dielectric ceramic elements of this type are made are wellknown in the art. Therefore, suitable materials and temperatures are notlisted exhaustively. All such suitable materials and process for makingsuch rods, cylinders and similar elements of this type are intended tobe within the scope of the invention.

At step 306, the disc can be combined into the dielectric substrate withthe aperture. For example, the outside surface of the disc can bemachined to ensure it is of an outside diameter (OD) that is less thanthe inside diameter (ID) of the substrate aperture. In some embodiments,the OD is slightly smaller than the ID to enable the disc to be insertedinto the substrate.

In some embodiments, the pre-fired disc can be received in an unfired or“green” substrate to form the composite assembly 100 shown in FIGS.4A-B.

At step 308, the disc and substrate can be co-fired. That is, compositeassembly 100 is fired. The co-firing temperature can be lower than thetemperature at which disc was fired, to ensure that the physical andelectrical properties of the disc remain unchanged. The co-firingtemperature can be within the well-known range in which such componentsare conventionally fired. Importantly, co-firing causes the substrate toshrink around the disc, thereby securing them together. Afterwards, theoutside surface of the composite assembly 100 can then be machined toensure it is of a specified or otherwise predetermined OD. Further, thisstep can be used to metalize and/or magnetize the composite assembly 100if the ferrite disc has not previously been magnetized.

Steps 310 and 312 show optional steps that can be taken after theco-firing of the composite assembly 100. For example, additionalcomponents can be added 310 onto the substrate, such as circuitry, toform final electronic components. Further, in some embodiments thecomposite assembly 100 can be sliced 312, or otherwise partitioned, toform a number of discrete assemblies. In some embodiments, both theseoptional steps can be performed and the particular order is notlimiting. In some embodiments, only one of the optional steps can betaken. In some embodiments, neither of the optional steps can be taken.

Accordingly, composite assemblies 100 can be used in manufacturing highfrequency electronic components in the same manner asconventionally-produced assemblies of this type. However, the method ofthe present invention is more economical than conventional methods, asthe invention does not involve the use of adhesives.

FIG. 24 illustrates an example embodiment of a circulator as discussedherein. Thick film silver can be printed as the circuit. As per standardcirculator applications, the circulator includes Port 1, Port 2, andPort 3. One of these ports can be blocked off to form an isolator.

Telecommunication Base Station

Circuits and devices having one or more features as described herein canbe implemented in RF applications such as a wireless base-station. Sucha wireless base-station can include one or more antennas configured tofacilitate transmission and/or reception of RF signals. Such antenna(s)can be coupled to circuits and devices having one or morecirculators/isolators as described herein.

Thus, in some embodiments, the above-disclosed material can beincorporated into different components of a telecommunication basestation, such as used for cellular networks and wireless communications.An example perspective view of a base station 2000 is shown in FIG. 25 ,including both a cell tower 2002 and electronics building 2004. The celltower 2002 can include a number of antennas 2006, typically facingdifferent directions for optimizing service, which can be used to bothreceive and transmit cellular signals while the electronics building2004 can hold electronic components such as filters, amplifiers, etc.discussed below. Both the antennas 2006 and electronic components canincorporate embodiments of the disclosed ceramic materials.

FIG. 25 shows a base station. The base station can include an antennathat is configured to facilitate transmission and/or reception of RFsignals. Such signals can be generated by and/or processed by atransceiver. For transmission, the transceiver can generate a transmitsignal that is amplified by a power amplifier (PA) and filtered (TxFilter) for transmission by the antenna. For reception, a signalreceived from the antenna can be filtered (Rx Filter) and amplified by alow-noise amplifier (LNA) before being passed on to the transceiver. Inthe example context of such Tx and Rx paths, circulators and/orisolators having one or more features as described herein can beimplemented at or in connection with, for example, the PA circuit andthe LNA circuit. The circulators and isolators can include embodimentsof the material disclosed herein. Further, the antennas can include thematerials disclosed herein, allowing them to work on higher frequencyranges.

FIG. 26 illustrates hardware 2010 that can be used in the electronicsbuilding 2004, and can include the components discussed above withrespect to FIG. 25 . For example, the hardware 2010 can be a basestation subsystem (BSS), which can handle traffic and signaling for themobile systems.

FIG. 27 illustrates a further detailing of the hardware 2010 discussedabove. Specifically, FIG. 27 depicts a cavity filter/combiner 2020 whichcan be incorporated into the base station. The cavity filter 2020 caninclude, for example, bandpass filters such as those incorporatingembodiments of the disclosed material, and can allow the output of twoor more transmitters on different frequencies to be combined.

FIG. 28 illustrates a circuit board 30004 which can include anisolator/circulator/filter 3002 and can be incorporated into the basestation discussed above.

From the foregoing description, it will be appreciated that inventiveproducts and approaches for composite microstrip circulators/isolators,materials, and methods of production are disclosed. While severalcomponents, techniques and aspects have been described with a certaindegree of particularity, it is manifest that many changes can be made inthe specific designs, constructions and methodology herein abovedescribed without departing from the spirit and scope of thisdisclosure.

Certain features that are described in this disclosure in the context ofseparate implementations can also be implemented in combination in asingle implementation. Conversely, various features that are describedin the context of a single implementation can also be implemented inmultiple implementations separately or in any suitable subcombination.Moreover, although features may be described above as acting in certaincombinations, one or more features from a claimed combination can, insome cases, be excised from the combination, and the combination may beclaimed as any subcombination or variation of any subcombination.

Moreover, while methods may be depicted in the drawings or described inthe specification in a particular order, such methods need not beperformed in the particular order shown or in sequential order, and thatall methods need not be performed, to achieve desirable results. Othermethods that are not depicted or described can be incorporated in theexample methods and processes. For example, one or more additionalmethods can be performed before, after, simultaneously, or between anyof the described methods. Further, the methods may be rearranged orreordered in other implementations. Also, the separation of varioussystem components in the implementations described above should not beunderstood as requiring such separation in all implementations, and itshould be understood that the described components and systems cangenerally be integrated together in a single product or packaged intomultiple products. Additionally, other implementations are within thescope of this disclosure.

Conditional language, such as “can,” “could,” “might,” or “may,” unlessspecifically stated otherwise, or otherwise understood within thecontext as used, is generally intended to convey that certainembodiments include or do not include, certain features, elements,and/or steps. Thus, such conditional language is not generally intendedto imply that features, elements, and/or steps are in any way requiredfor one or more embodiments.

Conjunctive language such as the phrase “at least one of X, Y, and Z,”unless specifically stated otherwise, is otherwise understood with thecontext as used in general to convey that an item, term, etc. may beeither X, Y, or Z. Thus, such conjunctive language is not generallyintended to imply that certain embodiments require the presence of atleast one of X, at least one of Y, and at least one of Z.

Language of degree used herein, such as the terms “approximately,”“about,” “generally,” and “substantially” as used herein represent avalue, amount, or characteristic close to the stated value, amount, orcharacteristic that still performs a desired function or achieves adesired result. For example, the terms “approximately”, “about”,“generally,” and “substantially” may refer to an amount that is withinless than or equal to 10% of, within less than or equal to 5% of, withinless than or equal to 1% of, within less than or equal to 0.1% of, andwithin less than or equal to 0.01% of the stated amount. If the statedamount is 0 (e.g., none, having no), the above recited ranges can bespecific ranges, and not within a particular % of the value. Forexample, within less than or equal to 10 wt./vol. % of, within less thanor equal to 5 wt./vol. % of, within less than or equal to 1 wt./vol. %of, within less than or equal to 0.1 wt./vol. % of, and within less thanor equal to 0.01 wt./vol. % of the stated amount.

Some embodiments have been described in connection with the accompanyingdrawings. The figures are drawn to scale, but such scale should not belimiting, since dimensions and proportions other than what are shown arecontemplated and are within the scope of the disclosed inventions.Distances, angles, etc. are merely illustrative and do not necessarilybear an exact relationship to actual dimensions and layout of thedevices illustrated. Components can be added, removed, and/orrearranged. Further, the disclosure herein of any particular feature,aspect, method, property, characteristic, quality, attribute, element,or the like in connection with various embodiments can be used in allother embodiments set forth herein. Additionally, it will be recognizedthat any methods described herein may be practiced using any devicesuitable for performing the recited steps.

While a number of embodiments and variations thereof have been describedin detail, other modifications and methods of using the same will beapparent to those of skill in the art. Accordingly, it should beunderstood that various applications, modifications, materials, andsubstitutions can be made of equivalents without departing from theunique and inventive disclosure herein or the scope of the claims.

What is claimed is:
 1. A composite material for use as a radiofrequencycomponent comprising: a rod including a magnetic garnet material; and aring surrounding the rod, the ring being formed from a scheelitematerial having a firing temperature of 950° C. or below.